Tropism (slide share)

Definition of Tropism, its common types and examples.

1. Tropism a growth response which a plant makes with respect to a directional stimulus. plant movement towards or away from a stimulus. came from the Greek word “ tropos ” which means to turn.

2. Tropism Positive Tropism towards the stimulus Negative Tropism away from stimulus Types of Tropism : Phototropism Geotropism Thigmotropism Hydrotropism

3. Phototropism movement towards or away from light t ropos = to turn photo = light Importance: Increases the probability of stems and leaves intercepting light for photosynthesis Roots obtain water and dissolved minerals that they need.

4. Phototropism

5. Geotropism movement towards or away from the earth t ropos = to turn geo = earth Importance: Roots will be more likely to encounter water and minerals, Stems and leaves will be better able to intercept light for photosynthesis.

6. Geotropism

7. Thigmotropism movement towards or away from touch t ropos = to turn thigma = touch Importance: Thigmotropism by tendrils allows plants to “climb” objects and thereby increases their chances of intercepting light for photosynthesis.

8. Thigmotropism Positive Thigmotropism

9. Thigmotropism Negative Thigmotropism

10. Hydrotropism movement towards or away from water t ropos = to turn hyrdro = water Importance: This ability to bend and grow the root towards a moisture gradient is essential because plants need water to grow.

11. Hydrotropism